Voice communication is typically conducted over the Public Switched Telephone Network (PSTN), in which a virtual dedicated circuit is established for each call. In such a circuit, a real-time connection is established that allows two-way transmission of data during the telephone call. Data communication can also be performed on such virtual circuits. However, data communication is increasingly being performed on wide-area data networks, such as the Internet, which provide a widely available and low-cost shared communications medium. Voice communications over such data networks is possible and is attractive because of the potentially lower cost of communicating over data networks, and the simplicity and lower cost of performing data and voice communications over a single network. However, the real-time nature of voice communications, coupled with the bandwidth required for such communication, often makes use of data networks for voice communication impractical. The bandwidth required for conventional voice communication also limits the use of services such as video conferencing which require significant additional amounts of bandwidth.
Accordingly, there is a need for techniques that reduce the amount of transmitted data required for voice communications.